Improve comments
Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/3rdparty/everest/library/Hacl_Curve25519_joined.c b/3rdparty/everest/library/Hacl_Curve25519_joined.c
index 149e474..957294f 100644
--- a/3rdparty/everest/library/Hacl_Curve25519_joined.c
+++ b/3rdparty/everest/library/Hacl_Curve25519_joined.c
@@ -19,9 +19,12 @@
* This file is part of mbed TLS (https://tls.mbed.org)
*/
#ifndef _BSD_SOURCE
-#define _BSD_SOURCE /* Required to enable compilation under --std=c99 */
+/* Required to get htole64() from gcc/glibc's endian.h (older systems)
+ * when we compile with -std=c99 */
+#define _BSD_SOURCE
#endif
#ifndef _DEFAULT_SOURCE
+/* (modern version of _BSD_SOURCE) */
#define _DEFAULT_SOURCE
#endif